The highly reactive nature of single-element semiconductor surfaces, namely silicon surfaces, creates a continuing need and challenge for controlled derivatization of these surfaces. Such processes should be adaptable for automated production and thus should include features such as ease of chemical derivatization and low process costs. Moreover, any electronic or other chemical features of an article having a derivatized surface should be maintained after derivatization. For example, there is a heightened interest in porous silicon due to its luminescent properties, and promise of compatibility with current semiconductor fabrication schemes based on silicon. Thus, there is a need for facile methods for derivatizing this surface.
The formation of Group IV element surfaces covalently terminated with organic groups is one desired derivatization process, e.g., a surface having silicon-carbon bonds. Silicon-carbon bonds can be accessed through hydrogen-terminated surfaces (i.e., having silicon-hydride bonds). Typically, however, substitution of silicon-hydride bonds with silicon-carbon bonds requires intermediate process steps prior to addition of the carbon-containing reagent. In at least one known case, a chlorination pretreatment step is required at temperatures of at least 80.degree. C. prior to silicon-carbon bond formation. The resulting chlorinated silicon surface is more sensitive to water and is not as easily manipulated compared to silicon-hydride surfaces. Other techniques for the formation of silicon-methyl surfaces are carried out through the addition of a Grignard reagent, CH.sub.3 MgBr but only in the presence of a photo- or electrochemical stimulus.
In other applications, there remains a challenge to provide an intimate integration between semiconductors and conducting polymers for efficient electrical and optical coupling. Conducting polymers offer distinct advantages over other conducting materials in that the physical properties can be tailored in a relatively facile manner. Thus, unlike conventional metal/semiconductor contacts, the electrical properties can be manipulated through various parameters such as polymer type and dopant.
Typically, forming polymer/semiconductor junctions involves depositing the polymer on the semiconductor by spin-coating or electrochemical polymerization. In general, a high quality junction cannot be obtained by such traditional deposition techniques. The resulting junction often suffers from poor interfacial interactions that can diminish physical and electrical performance.
Other junctions have been formed with an intervening oxide layer. Simon et al. report an oxidized surface of silicon attached to a pyrrole-terminated alkylsiloxane monolayer via an oxide linkage and subsequently subjected to polymerization. The intervening oxide layer optimizes electrical and other physical properties of the polymer/semiconductor junction.
There remains a challenge to derivatize surfaces with various organic groups, in particular where the surface comprises a Group IV semiconductor. There also remains a need to lower costs for forming surfaces having silicon-carbon bonds.